Perez, considered by many as the key to the Mariners offence, is being given until the last moment to prove his fitness as he battles to overcome a hamstring injury sustained against the Gold Coast in the preliminary final.

With six goals and six assists for the season, 25-year-old Perez undoubtedly offers his side an extra dimension in attack, but Postecoglou says his likely replacement, 17-year-old Mustafa Amini, presents an almost identical skill set.

"I don't think there's a great deal (of difference). They've got Amini, who's pretty much like for like, so I don't expect them to change their formation or what they do against us, whether they play or not," he said.

"If we're expecting him and he doesn't play, so be it, and if it's the other way around, so be it. We're not going to worry too much about it."

"I don't think it'll change anything really, from a structural point of view. We'll just focus on our structure, their structure, and not worry too much about the individuals."

But while Postecoglou says Brisbane's won't be changing their plan or structure regardless of whether or not Perez plays, substitute midfielder Massimo Murdocca certainly believes the Mariners are a better team with their Argentine import on the field.

"I remember the first game, he didn't play, and he was definitely a big loss for them. It was the 5-1 result that we had when he wasn't playing and you can just tell he's a big player for them," said Murdocca.

"He's one we've definitely got to watch out for (if he plays). He's definitely one that has made them more of a threat for us. We've got to make sure that we handle him."

Should Perez be cleared to start as attacking midfielder, Brisbane's containment specialist Erik Paartalu will be charged with the assignment of limiting his impact.

Both Paartalu and Murdocca said that honours had been shared over the two-leg major semi-final, with Paartalu getting on top in the first leg at Bluetongue Stadium, before Perez returned the favour in the second clash at Suncorp Stadium in a thrilling 2-2 result.

"Erik has got the main responsibility and he's done a good job, but it's been 50-50 to be honest. Perez has had an influence and then Erik has had an influence," said Murdocca.

"Hopefully on the weekend it'll be Erik that stands tall at the end of the day. It'll be a good contest to see."

Paartalu agreed with both his coach and teammate, saying not much would change whether Amini or Perez took the field.

However, if Perez made the starting line-up, Paartalu said he'd be working on refining his tactics to ensure he finished on top in the pivotal match-up.

"If Perez plays, it'll be better for them, but if Amini plays, he's the same sort of player and he poses the same threat," he said.

"I think I should maybe not to take him so literally, in terms of marking him and trying to mark him out of the game, and focus a bit more on my stuff, what I can do going forward, and cause him some problems."

"The first leg I did cause him a lot of problems by dropping deep, getting the ball and opening up spaces, but the second game it didn't really work too well, so we'll have a new formula."